1. Field of the Invention
The present invention relates to an intake air control valve attached to a communication hole on a partition wall provided in a surge tank of a multiple cylinder internal combustion engine via a seal member, and relates to a seal member used there.
2. Description of Related Art
In conventional, in a multiple cylinder internal combustion engine, there has been known an intake air apparatus in which a partition wall is formed in an inner portion of a surge tank, a first surge tank chamber and a second surge tank chamber are formed within the surge tank, an intake air control valve is arranged in a communication hole formed on the partition wall, the first surge tank chamber and the second surge tank chamber are separated by fully closing the intake air control valve, and the first surge tank chamber and the second surge tank chamber are communicated with each other by fully opening the intake air control valve.
This intake air apparatus controls the intake air control valve so as to fully close or fully open the intake air control valve in correspondence to a high load low speed operation of the internal combustion engine or a low load high speed operation of the internal combustion engine, thereby changing an equivalent pipe length of an intake air passage. Thus, the intake air apparatus is controlled so as to secure a high charging efficiency all over an entire rotating speed area of the internal combustion engine by utilizing an intake air inertia effect.
In the intake air control valve used in this kind of intake air apparatus, if an air leakage is generated at a time when the intake air control valve is fully closed, the intake air inertia effect is weakened and it is impossible to sufficiently increase the charging effect. Accordingly, a high sealing property is required at a time when the intake air control valve is fully closed, and a valve body (a butterfly valve) of the intake air control valve is structured such that a high sealing property can be obtained at the time of full closing mentioned above.
Further, in an actual surge tank, in the case of attaching the intake air control valve mentioned above to the communication hole on the partition wall of the surge tank, it is necessary to assemble while securing a high sealing property. Therefore, in conventional, there is employed a structure in which this kind of intake air control valve is provided with a valve holder, a butterfly valve is rotatably attached to a valve hole provided within the valve holder by a valve shaft, and the valve holder is attached so as to be fitted to a communication hole (a notch-like opening portion) provided on the partition wall of the surge tank (refer, for example, to Japanese Utility Model Publication No. 6-39052). Further, the structure is made such that a groove is formed in a periphery of the valve holder, a string-like seal member is fitted to the groove, and the string-like seal member seals between an outer peripheral portion of the valve holder and an opening portion of the partition wall.
However, the string-like seal member fitted and attached to the periphery of the valve holder of this kind of conventional intake air control valve is used in a comparatively long part. Accordingly, in the case of using a general rubber seal member provided with a groove and a fin-like seal portion, there is a risk that the attaching position of the seal member is displaced due to a vibration of the engine, and the seal member falls away from the groove. Further, in the case of using the string-like seal member having a simple cross sectional shape with a great elastic deformation resistance, a reaction force applied to the valve holder from the seal member becomes large at a time of attaching the valve holder to the opening portion of the partition wall, whereby there is a problem that a deformation is generated in the valve holder and the sealing property at the time of full closing is deteriorated.
In order to achieve the object mentioned above, in accordance with the present invention, there is provided an intake air control valve in which a partition wall separating a surge tank chamber is formed in an inner portion of a surge tank of a multiple cylinder internal combustion engine, an intake air control valve having a valve holder and independently formed from the partition wall is attached by fitting and inserting the valve holder to a communication hole formed on the partition wall, a valve hole is formed within the valve holder, a butterfly-shaped valve body is pivoted via a valve shaft so as to freely open and close the valve hole, and a seal member is fitted to a groove provided in a peripheral edge portion of the valve holder, wherein the seal member is formed by a fitting and attaching portion fitted and attached to the groove of the valve holder, and a leading end seal portion brought into contact with an inner peripheral portion of the communication hole on the partition wall, and recess portions open to an inner side of the groove are provided in parallel in a longitudinal direction in the fitting and attaching portion so as to be separated by a plurality of ribs.
An object of the present invention is to provide an intake air control valve which can prevent the seal member fitted and attached to the peripheral edge portion of the valve holder from falling away and can secure an improved sealing property at a time of full closing, on the basis of the structure mentioned above.
The intake air control valve having the structure mentioned above is mounted to the communication hole provided on the partition wall within the surge tank in an intake air system of the multiple cylinder internal combustion engine so as to fit and attach the valve holder thereto. At this time, the valve holder of the intake air control valve brings the leading end seal portion of the seal member fitted and attached to the groove in the peripheral edge portion of the valve holder into contact with the inner side of the communication hole close to the partition wall, thereby sealing between the partition wall and an outer peripheral portion of the valve holder.
At this time, since the recess portions open to the inner side of the groove are sectioned by a plurality of ribs so as to be arranged in parallel in the longitudinal direction, the fitting and attaching portion of the seal member fitted and attached to the groove of the peripheral edge portion of the valve holder is held within the groove in a fitted and attached state with a proper elastic force. Therefore, it is possible to prevent the seal member from falling away due to the vibration or the like.
Further, an elastic force of the seal member, that is, a reaction force applied to the valve holder by the seal member, at a time when the fitting and attaching portion is fitted and attached to the inner side of the groove or at a time when the valve holder is fitted to the communication hole, is reduced to a suitable magnitude by the recess portions provided in the fitting and attaching portion of the seal member and the ribs arranged between the recess portions. Accordingly, at a time of fitting the valve holder into the communication hole, the valve holder is not deformed by the reaction force applied by the seal member. Therefore, it is possible to prevent the valve holder from being deformed, it is possible to hold the seal member in the proper seal position, and it is possible to secure a high sealing property at a time when the valve body within the valve holder is fully closed.